Cerebellar lncRNA Expression Profile Analysis of SCA3/MJD Mice

Polyglutamine-expanded ataxin3 alter specific gene expressions through changing DNA methylation status in SCA3/MJD

DNA methylation has recently been linked to transcriptional dysregulation and neuronal dysfunction in polyglutamine (polyQ) disease. This study aims to determine whether (CAG)_n expansion in ATXN3 perturbs DNA methylation status and affects gene expression. We analyzed DNA methylation throughout the genome using reduced representation bisulfite sequencing (RRBS) and confirmed the results using MethylTarget sequencing. Dynamic changes in DNA methylation, transcriptional and translational levels of specific genes were detected using BSP, qRT-PCR and western blot. In total, 135 differentially methylated regions (DMRs) were identified between SCA3/MJD and WT mouse cerebellum. KEGG analysis revealed differentially methylated genes involved in amino acid metabolism, Hedgehog signaling pathway, thyroid cancer, tumorigenesis and other pathways. We focused on DMRs that were directly associated with gene expression. On this basis, we further assessed 7 genes, including 13 DMRs, for DNA methylation validation and gene expression. We found that the methylation status of the DMRs of En1 and Nkx2-1 was negatively associated with their transcriptional and translational levels and that alteration of the DNA methylation status of DMRs and the corresponding transcription occurred before dyskinesia in SCA3/MJD mice. These results revealed novel DNA methylation-regulated genes, En1 and Nkx2-1, which may be useful for understanding the pathogenesis of SCA3/MJD.

Identification of a potential exosomal biomarker in spinocerebellar ataxia Type 3/Machado-Joseph disease

Aim: To identify spinocerebellar ataxia Type 3 (SCA3)-related exosomal biomarkers and the underlying mechanisms. Materials & methods: Exosomal RNAs from plasma and cerebrospinal fluid (CSF) were extracted from 24 SCA3 patients and 22 controls, respectively. Small RNA sequencing and quantitative PCR verification were performed. Gene ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway analyses of the results were carried out. Results: One novel miRNA is notably downregulated in plasma-derived exosomes, while upregulated in CSF-derived exosomes of SCA3 patients. Besides, it is successively upregulated in CSF-derived exosomes from Type 1, Type 2 and Type 3 groups. The downstream target genes were enriched in protein processing in endoplasmic reticulum and axon guidance. Conclusion: One exosomal biomarker was identified in SCA3, and this is the first time to report an exosomal miRNA as a biomarker in SCA3 internationally.

Is the High Frequency of Machado-Joseph Disease in China Due to New Mutational Origins?

Machado-Joseph disease (MJD, also known as spinocerebellar ataxia 3 or SCA3) is the most common dominant ataxia worldwide, with an overall average prevalence of 1–5/100,000. To this date, two major ancestral lineages have been found throughout the world. In China, the relative frequency of MJD among the SCAs reaches as high as 63%, however, little is known about its mutational origin in this country. We analyzed 50 families with MJD patients in two or more generations to study the hypothesis that new mutational events have occurred in this population. Haplotypes based on 20 SNPs have shown new genetic backgrounds segregating with MJD mutations in our cohort from China. We found the “Joseph-derived” lineage (Joseph lineage with a G variant in rs56268847) to be very common among Chinese MJD patients. Moreover, we estimated the time for the origin of this MJD SNP background based on STR diversity flanking the (CAG)_n of ATXN3. It was surprising to find that the Chinese MJD population originated from 8,000 to 17,000 years ago, far earlier than the previous literature reports, which will be an important evidence to explain the origin, spread and founder effects of MJD.

Nonlinear analysis of local field potentials and motor cortex EEG in spinocerebellar ataxia 3

This study explores the potential usefulness of EEG for patient diagnosis by analyzing SCA3 and wt mice. Self-made implantable electrodes were constructed and implanted to extract EEG signals from the cerebral motor cortex and the cerebellar areas that are affected by the disease. Nonlinear dynamic analysis and EEG energy were used to distinguish between SCA3 and WT mice, and we found that all four were increased in SCA3 mice. The alpha and theta bands of LZ complexity were significantly higher in SCA3 mice than in the control group. Therefore, it was possible to distinguish between the two groups by the LZ complexity of their alpha and theta bands. Analysis of C₀ complexity and approximate entropy showed that the random part in the disease group was larger than in the control group, and that in addition the randomness was increased in SCA3 mice. The spatial learning and memory were analyzed by means of the Morris water maze test (MWM), The results showed that the swimming velocity, distance traveled and latency to reach the platform in SCA3 mice were increased when compared with WT mice during the 4 training days (p < 0.05, 0.01 or 0.001). And the results are conform to the results of EEG signals. In conclusion, EEG signals could be used to identify SCA3 in mice. They may also be clinically useful for the diagnosis of cerebellar ataxia in patients, and for additional studies aimed at gaining a deeper understanding of spinal cerebral ataxia.